Method for repairing roller surface of withdrawal and straightening roller of continuous casting machine and alloy powder

Abstract

The invention relates to the technical field of withdrawal and straightening roller repairing, in particular to a continuous casting machine withdrawal and straightening roller surface repairing method and alloy powder. According to the repairing method provided by the invention, the roller surface of the pulling-straightening roller is firstly pretreated, and then the pretreated roller surface of the pulling-straightening roller is repaired by adopting laser cladding. Alloy powder is used during laser cladding, so that the high-temperature resistance, wear resistance, high-temperature creep resistance and other properties of a cladding layer are improved, and the service life of the withdrawal and straightening roller is prolonged. The invention further provides alloy powder which is high-carbon iron-based alloy powder containing tungsten, titanium, molybdenum, niobium, silicon, boron and rare earth elements, the alloy powder is used for repairing the roller surface of the withdrawal and straightening roller, and a formed cladding layer has excellent high-temperature resistance. The alloy powder is cladded on the roller surface of the withdrawal and straightening roller by adopting a laser cladding technology to form a functional layer, so that the online steel passing amount and the service life of the withdrawal and straightening roller are remarkably improved.

Description

Technical Field

[0001] The invention relates to the technical field of repairing a straightening roller, and in particular to a repairing method for the roller surface of a straightening roller of a continuous casting machine and alloy powder. Background Art

[0002] The temperature in the steelmaking continuous casting production area is relatively high, and the straightening rollers are severely worn, limiting their service life. For straightening rollers with relatively small wear, they can continue to be used after repair. The repair and reuse of straightening rollers can effectively reduce costs.

[0003] The traditional maintenance method is to weld iron-based wear-resistant electrodes to restore the size and functional layer. The surface of the straightening roller after repair will be worn out and fail in 2 to 3 months. How to improve the high temperature strength and wear resistance of the repaired straightening roller surface and extend the service life of the straightening roller after repair has become a technical problem that technicians in this field need to solve. Summary of the invention

[0004] The purpose of the present invention is to provide a method for repairing the roller surface of a straightening roller of a continuous casting machine and alloy powder, and to repair the roller surface of the straightening roller by laser cladding, thereby improving the high temperature strength and wear resistance of the straightening roller, and thus extending the service life of the straightening roller. In order to solve the problems and shortcomings existing in the prior art, the present invention provides a method for repairing the roller surface of a straightening roller of a continuous casting machine. The above-mentioned repair method comprises the following steps:

[0005] Pre-treating the surface of the straightening roller;

[0006] The surface of the straightening roller is laser clad using alloy powder.

[0007] Optionally, the laser cladding of the roller surface of the straightening roller includes:

[0008] Preheating treatment: preheating the roller surface for cladding, the preheating time is about 20 to 30 minutes, and the preheating temperature is 120 to 150 ° C;

[0009] Formulate a cladding plan, plan the cladding method and cladding path, the cladding method is to use iron-based powder with a hardness of HRC36-40 to lay the base layer, and then use alloy powder for cladding; the cladding path is to use iron-based powder with a hardness of HRC36-40 to rotate and clad along the radial direction of the roller surface, and then use a spiral circle method, along the axial direction of the straightening roller, and unidirectional cladding;

[0010] Prepare a cladding program, and prepare the cladding program according to the cladding plan;

[0011] Laser cladding, cladding a bottom layer and a functional layer on the surface of the straightening roller in sequence according to the cladding procedure, wherein the material of the bottom layer is iron with a HRC of 36 to 40, and the material of the functional layer is alloy powder;

[0012] After cladding, the cladding surface is treated to remove powder residue, and then the surface forming quality and size of the cladding layer are inspected, and then the cladding layer is wrapped with insulation materials and unloaded and placed on a bracket for slow cooling.

[0013] Optionally, the laser source of the laser cladding is a fiber laser, the powder feeding method is air-borne coaxial powder feeding, and the gas source is argon.

[0014] Optionally, the pretreatment of the surface of the straightening roller includes:

[0015] Removing cracks and fatigue layers from the surface of the straightening roller;

[0016] Grinding and flaw detection of the cracks and fatigue layers;

[0017] After confirming that the straightening roller is not damaged, the roller surface and the surface of the straightening roller are cleaned with acetone and dried.

[0018] Optionally, the parameters of the laser cladding include:

[0019] The cladding power is 4500-5200W, the spot diameter is 3.8-4.2mm, the cladding line speed is 30-50mm / s, the cladding powder feeding amount is 45-60g / min, the cladding powder feeding gas flow rate is 5-7NL / min, the cladding shielding gas flow rate is 15-20NL / min, the cladding overlap rate is 35%-50%, and the single layer thickness is 2-3.5mm. Furthermore, the present invention also provides an alloy powder for repairing the roller surface of a straightening roller, wherein the alloy powder is a high-carbon iron-based alloy, and the high-carbon iron-based alloy contains tungsten, titanium, molybdenum, niobium, silicon, boron, and rare earth elements.

[0020] Optionally, the composition of the alloy powder is: C: 3.6-6.5%, Cr: 11.5-13.7%, W: 13.2-16.7%, Mo: 8.6-11.5%, Mn: 2.2-5%, Ti: 34.6-41.2%, Si: 0.3-0.7%, Ni: 4.5-7.3%, Nb: 2-4.5%, V: 0.8-1.2%, B: 0.5-2%, rare earth elements (Sc, Hf, Ce) 0.8-2.5%, and the balance is iron Fe.

[0021] Optionally, the alloy powder has a particle size of 50-250 mesh.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] (1) Laser cladding is used to repair the straightening roller. The cladding layer is metallurgically bonded to the substrate, which can significantly improve the wear resistance, corrosion resistance, heat resistance, and oxidation resistance of the substrate surface, improve the high temperature strength and wear resistance of the straightening roller, and thus extend the service life of the straightening roller.

[0024] (2) High carbon iron-based alloy powder containing tungsten, titanium, molybdenum, niobium, silicon, boron and rare earth elements is used to repair the surface of the straightening roller. The formed cladding layer has excellent high temperature resistance, high temperature wear resistance, high temperature fatigue resistance, high temperature corrosion resistance, crack resistance, impact resistance, and adhesion resistance. The alloy powder is clad on the surface of the straightening roller using laser cladding technology to form a functional layer, which significantly improves the online steel passing capacity and service life of the straightening roller.

[0025] Based on the following detailed description of specific embodiments of the present invention in conjunction with the accompanying drawings, those skilled in the art will become more aware of the above and other objects, advantages and features of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Hereinafter, some specific embodiments of the present invention will be described in detail in an exemplary and non-limiting manner with reference to the accompanying drawings. The same reference numerals in the accompanying drawings indicate the same or similar components or parts. It should be understood by those skilled in the art that these drawings are not necessarily drawn to scale. In the accompanying drawings:

[0027] Figure 1 is a flow chart of a repair method according to an embodiment of the present invention;

[0028] Figure 2 is a flow chart of the pretreatment of the roller surface of a straightening roller according to an embodiment of the present invention;

[0029] Figure 3 This is a process flow chart of laser cladding on the surface of a straightening roller according to an embodiment of the present invention;

[0030] Figure 4 It is a metallographic picture of the cladding structure of one embodiment of the present invention. DETAILED DESCRIPTION

[0031] Refer to the following Figures 1 to 4 To describe a method for repairing the roller surface of a continuous casting machine straightening roller and alloy powder according to an embodiment of the present invention. In the description of this embodiment, it should be understood that the terms "first" and "second" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features, that is, include one or more of the features. In the description of the present invention, the meaning of "multiple" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined. When a feature "includes or contains" one or some of the features it covers, unless otherwise specifically described, this indicates that other features are not excluded and may further include other features.

[0032] In the description of the present embodiment, the description with reference to the terms "one embodiment", "some embodiments", "illustrative embodiments", "examples", "specific examples", or "some examples" means that the specific features, structures, materials, or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described may be combined in any one or more embodiments or examples in a suitable manner.

[0033] Figure 1 Schematic diagram of the structure of a reflective mask according to an embodiment of the present invention. Figure 1 As shown, the present invention provides a method for repairing the roller surface of a continuous casting machine straightening roller, and the above-mentioned repair method comprises:

[0034] Step S10, pre-treating the roller surface of the straightening roller;

[0035] Step S30, using alloy powder to laser clad the roller surface of the straightening roller.

[0036] The specific working process of this embodiment is as follows: first, the surface of the straightening roller is pretreated to remove cracks, scratches and other defects on the surface of the straightening roller, so that the straightening roller is undamaged. Secondly, alloy powder is selected as the cladding material, and the straightening roller is repaired by laser cladding on the surface of the straightening roller.

[0037] In this embodiment, laser cladding is used to repair the straightening roller. The cladding layer is metallurgically bonded to the substrate, which can significantly improve the wear resistance, corrosion resistance, heat resistance, and oxidation resistance of the substrate material surface, improve the high temperature strength and wear resistance of the straightening roller, and thus extend the service life of the straightening roller.

[0038] like Figure 3 As shown, in some embodiments of the method for repairing the roller surface of a straightening roller of a continuous casting machine of the present invention, the laser cladding of the roller surface of the straightening roller comprises:

[0039] Step S31, preheating treatment, using an induction heater to preheat the roller surface at the beginning of cladding, preheating time: about 20 to 35 minutes, preheating temperature: 120 to 150 ° C;

[0040] Step S32, formulate a cladding plan, plan a cladding method and a cladding path, the cladding method is to use an iron-based powder with a hardness of HRC36-40 as a base layer, and then use alloy powder for cladding; the cladding path is to use an iron-based powder with a hardness of HRC36-40 to rotate and clad along the radial direction of the roller surface, and then use a spiral circle method, along the axial direction of the straightening roller, and unidirectional cladding;

[0041] Step S33, compiling a cladding program, compiling the cladding program according to the cladding plan;

[0042] Step S34, laser cladding, cladding the bottom layer and the functional layer on the surface of the straightening roller in sequence according to the cladding procedure, wherein the material of the bottom layer is iron with a HRC of 36 to 40, and the material of the functional layer is alloy powder;

[0043] Step S35, post-cladding treatment, removes powder residue from the cladding surface, checks the surface molding quality and size of the cladding layer, wraps with insulation material, unloads and places on a bracket for slow cooling.

[0044] The specific cladding process includes: first, preheating the straightening roller before cladding to make the straightening roller have a certain actual temperature. Secondly, formulate a cladding plan and complete the preparation of the cladding program. Thirdly, cladding is carried out according to the preset cladding program. Finally, after the cladding is completed, post-cladding treatment is carried out to remove the residual powder on the surface of the cladding layer and inspect the quality and size of the cladding layer.

[0045] In this embodiment, a cladding plan is formulated, and a cladding program is compiled according to the cladding plan, so that the entire cladding process is completed under automatic control, errors caused by human factors are avoided, and the quality of the cladding layer can be guaranteed.

[0046] In some embodiments of the method for repairing the roller surface of a continuous casting machine straightening roller of the present invention, the laser source of the laser cladding is a fiber laser, the powder feeding method is air-borne coaxial powder feeding, and the gas source is argon.

[0047] Coaxial powder feeding technology means that the laser is output from the center of the cladding head, and the metal powder is distributed in a ring around the laser or in multiple beams around the circumference. The cladding head is equipped with a special protective gas channel and alloy powder channel. During cladding, the alloy powder and the laser intersect at a point outside the cladding head, that is, the laser and the alloy powder act on the surface of the substrate, and the alloy powder and the substrate are melted at the same time under the action of the laser, forming a cladding layer on the surface of the workpiece.

[0048] In this embodiment, coaxial powder feeding is used, the inert gas protection effect of the molten pool is good, the molten pool is small, the powder is heated evenly, and the cladding layer has good crack resistance.

[0049] like Figure 2 As shown, in some embodiments of the method for repairing the roller surface of a straightening roller of a continuous casting machine of the present invention, the pretreatment of the roller surface of the straightening roller includes:

[0050] Step S11, removing cracks and fatigue layers on the surface of the straightening roller;

[0051] Step S12, grinding and flaw detection of the crack and fatigue layer;

[0052] Step S13, after determining that the straightening roller is not damaged, the roller surface and the surface of the straightening roller are cleaned with acetone and dried.

[0053] In this embodiment, the roller surface of the straightening roller is cleaned and dried before cladding to remove oil, rust and other contaminants on the roller surface. These contaminants will hinder the effective combination of the cladding material and the straightening roller surface, causing the cladding layer to be prone to cracks, peeling and other problems. Cleaning and drying before cladding can form a good metallurgical bond between the cladding layer and the straightening roller surface, thereby improving the quality and durability of the cladding layer.

[0054] In some embodiments of the present invention, first, a lathe is used to turn the cracks and fatigue layer on the surface of the straightening roller. Secondly, the roller surface is ground around 2 to 3 mm after turning, and then a flaw detection test is performed. If there are defects such as cracks, pores, inclusions, etc., the turning is repeated to remove them. If the inspection results show that there are no defects such as cracks, pores, inclusions, etc., the straightening roller is cleaned.

[0055] In other embodiments of the present invention, after the roller surface of the straightening roller is free of defects such as cracks, pores, inclusions, etc., the straightening roller is clamped on a turntable laser cladding equipment, and then the roller surface and the surrounding surface are cleaned with acetone to remove surface oil, floating rust and other debris, and then dried.

[0056] In this embodiment, the straightening roller is clamped on the rotary table laser cladding equipment for cleaning and drying to avoid re-contamination during transportation after cleaning.

[0057] In some embodiments of the method for repairing the roller surface of a continuous casting machine straightening roller of the present invention, the process parameters of the laser cladding include: cladding power of 4500-5200 W, spot diameter of 3.8-4.2 mm, cladding line speed of 30-50 mm / s, cladding powder feeding amount of 45-60 g / min, cladding powder feeding gas flow rate of 5-7 NL / min, cladding protective gas flow rate of 15-20 NL / min, cladding overlap rate of 35%-50%, and single layer thickness of 2-3.5 mm.

[0058] In this embodiment, the above cladding parameter settings result in high overall cladding efficiency and good forming effect.

[0059] Furthermore, the present invention also provides an alloy powder for repairing the roller surface of a straightening roller, wherein the alloy powder is a high-carbon iron-based alloy, and the high-carbon iron-based alloy contains tungsten, titanium, molybdenum, niobium, silicon, boron, and rare earth elements. Adding Ni and Mo to the alloy can improve the high temperature resistance and high temperature wear resistance of the alloy. Adding Mo can improve the toughness and high temperature strength of the cladding layer, and the increase in Ni content can also significantly improve the process performance of the iron-based alloy powder. The Nb element forms niobium carbide in the cladding layer, which increases the wear resistance and fluidity of the cladding layer, and the cladding forming effect is smoother. Adding trace elements Si, B, and V can improve the laser cladding processability and the fluidity of the cladding layer, reduce the cracking of the cladding layer and refine the grains, while improving the wear resistance. Adding trace rare earth elements Sc, Hf, and Ce can purify the alloy cladding layer, reduce harmful impurities, refine the grains and strengthen the grain boundaries, improve the impact toughness and prevent the occurrence of cracks in the cladding layer, while improving the high temperature stability, high temperature endurance strength, and wear resistance of the cladding layer.

[0060] In this embodiment, high carbon iron-based alloy powder containing tungsten, titanium, molybdenum, niobium, silicon, boron and rare earth elements is used to repair the surface of the straightening roller, and the formed cladding layer has excellent high temperature resistance, high temperature wear resistance, high temperature fatigue resistance, high temperature corrosion resistance, crack resistance, impact resistance, and adhesion resistance. The alloy powder is clad on the surface of the straightening roller by laser cladding technology to form a functional layer, which significantly improves the online steel passing capacity and service life of the straightening roller.

[0061] In some embodiments of the alloy powder of the present invention, the composition of the alloy powder is: C: 3.6-6.5%, Cr: 11.5-13.7%, W: 13.2-16.7%, Mo: 8.6-11.5%, Mn: 2.2-5%, Ti: 34.6-41.2%, Si: 0.3-0.7%, Ni: 4.5-7.3%, Nb: 2-4.5%, V: 0.8-1.2%, B: 0.5-2%, rare earth elements (Sc, Hf, Ce) 0.8-2.5%, and the balance is iron Fe.

[0062] In some embodiments of the alloy powder of the present invention, the particle size of the alloy powder is 50-250 mesh.

[0063] The particle size of alloy powder during laser cladding affects the density, surface quality and mechanical properties of the cladding layer. If the particle size is too large, the gaps between the heated powder particles will cause a capillary effect, making it impossible for the metal liquid to fully fill the gaps, thereby increasing the porosity of the formed part; at the same time, there will be larger particles on the surface of the cladding layer formed after heating, which will affect the surface finish of the formed part. If the particle size of the powder is too small, the powder particles will melt quickly during the heating process, making it difficult to control the density of the formed part, and cracks and defects will occur at the interface between the construction layers, thereby affecting the surface quality of the cladding layer. In addition, if the powder particle size is too small or too large, the strength of the cladding layer will be reduced.

[0064] In this embodiment, the particle size of the alloy powder is between 50 and 250 meshes, so that the cladding layer has a high density, a good surface finish, no defects such as cracks, and a high mechanical strength.

[0065] The present invention is specifically explained below using several embodiments, and the technical solutions in the embodiments of the present invention are clearly and completely described. The described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments.

[0066] Embodiment 1: A method for repairing the roller surface of a continuous casting machine straightening roller

[0067] Step S111, removing cracks and fatigue layers on the surface of the straightening roller;

[0068] Step S112, grinding and flaw detection of the crack and fatigue layer;

[0069] Step S113, after determining that the straightening roller is not damaged, the roller surface and the surface of the straightening roller are cleaned with acetone and dried.

[0070] Step S121, prepare alloy powder, the mass percentage of each chemical component in the alloy powder is C: 3.6%, Cr: 13.7%, W: 13.2%, Mo: 8.6%, Mn: 2.4%, Ti: 41.2%, Si: 0.3%, Ni: 4.5%, Nb: 2.3%, V: 0.81%, B: 0.55%, rare earth elements (Sc, Hf, Ce) 0.87%, and the balance is iron Fe. The alloy powder particle size: 50-250 mesh.

[0071] Step S131, preheating the roller surface for cladding, the preheating time is 20 minutes, and the preheating temperature is 120°C;

[0072] Step S132, formulate a cladding plan, use iron-based powder with a hardness of HRC36-40 to perform radial rotation cladding along the roller surface to form a base layer; then use alloy powder to perform unidirectional cladding in a spiral circle along the axial direction of the straightening roller.

[0073] Step S133, compiling a cladding program.

[0074] Step S134, performing laser cladding according to the cladding procedure.

[0075] Step S135, after the cladding is completed, the cladding surface is treated to remove powder residue, and then the surface molding quality and size of the cladding layer are inspected, and then the cladding layer is wrapped with insulation materials and unloaded and placed on a bracket for slow cooling.

[0076] It should be noted that in the embodiment, the process parameters of laser cladding are: laser power 4800 W, cladding spot size (circular): 3.8 mm, cladding line speed: 40 mm / s, powder feeding amount: 56 g / min, powder feeding gas flow rate: 7 L / min, shielding gas flow rate: 18 L / min, overlap rate: 45%, and cladding thickness 3.11 mm.

[0077] Embodiment 2: A method for repairing the roller surface of a continuous casting machine straightening roller

[0078] Step S211, removing cracks and fatigue layers on the surface of the straightening roller;

[0079] Step S212, grinding and flaw detection of the crack and fatigue layer;

[0080] Step S213, after determining that the straightening roller is not damaged, the roller surface and the surface of the straightening roller are cleaned with acetone and dried.

[0081] Step S221, prepare alloy powder, the mass percentage of each chemical component in the alloy powder is C: 4.5%, Cr: 12.3%, W: 14.2%, Mo: 10.2%, Mn: 2.8%, Ti: 36.4%, Si: 0.55%, Ni: 6.7%, Nb: 3.4%, V: 0.93%, B: 0.61%, rare earth elements (Sc, Hf, Ce) 1.4%. The balance is iron Fe. The alloy powder particle size: 50-250 mesh.

[0082] Step S231, preheating the roller surface for cladding, the preheating time is 20 minutes, and the preheating temperature is 120°C;

[0083] Step S232, formulate a cladding plan, use iron-based powder with a hardness of HRC36-40 to perform radial rotation cladding along the roller surface to form a base layer; then use alloy powder to perform unidirectional cladding in a spiral circle along the axial direction of the straightening roller.

[0084] Step S233, compiling a cladding program.

[0085] Step S234, performing laser cladding according to the cladding procedure.

[0086] Step S2235, after the cladding is completed, the cladding surface is treated to remove powder residue, and then the surface molding quality and size of the cladding layer are inspected, and then the cladding layer is wrapped with insulation materials and unloaded and placed on a bracket for slow cooling.

[0087] It should be noted that in the embodiment, the process parameters of laser cladding are: laser power 5000 W, cladding spot size (circular): 3.8 mm, cladding line speed: 42 mm / s, powder feeding amount: 50 g / min, powder feeding gas flow rate: 7 L / min, shielding gas flow rate: 18 L / min, overlap rate: 45%, and cladding thickness 3.10 mm.

[0088] Embodiment 3: A method for repairing the roller surface of a continuous casting machine straightening roller

[0089] Step S311, removing cracks and fatigue layers on the surface of the straightening roller;

[0090] Step S312, grinding and flaw detection of the crack and fatigue layer;

[0091] Step S313, after determining that the straightening roller is not damaged, the roller surface and the surface of the straightening roller are cleaned with acetone and dried.

[0092] Step S321, prepare alloy powder, the mass percentage of each chemical component in the alloy powder is C: 5.5%, Cr: 13.7%, W: 16.7%, Mo: 11.5%, Mn: 4.6%, Ti: 41.2%, Si: 0.7%, Ni: 7.3%, Nb: 3.2%, V: 1.1%, B: 1.23%, rare earth elements (Sc, Hf, Ce) 1.8%. The balance is iron Fe. The alloy powder particle size: 50-250 mesh.

[0093] Step S331, preheating the roller surface for cladding, the preheating time is 20 minutes, and the preheating temperature is 120°C;

[0094] Step S332, formulate a cladding plan, use iron-based powder with a hardness of HRC36-40 to perform radial rotation cladding along the roller surface to form a base layer; then use alloy powder to perform unidirectional cladding in a spiral circle along the axial direction of the straightening roller.

[0095] Step S333, compile cladding program.

[0096] Step S334, performing laser cladding according to the cladding procedure.

[0097] Step S335, after the cladding is completed, the cladding surface is treated to remove powder residue, and then the surface molding quality and size of the cladding layer are inspected, and then the cladding layer is wrapped with insulation materials and unloaded and placed on a bracket for slow cooling.

[0098] The cladding layers on the roller surfaces of the straightening rollers obtained in Example 1 to Example 3 were tested, and the hardness results at different temperatures are shown in Tables 1 to 3:

[0099] Table 1 Rockwell hardness of the cladding layer on the surface of the straightening roller obtained in the embodiment at different temperatures

[0100] temperature Room temperature 100℃ 200℃ 400℃ 600℃ 700℃ 800℃ Sample 1 46.21 45.26 43.37 41.22 39.52 37.61 31.56 Sample 2 46.27 45.30 43.42 40.86 39.24 36.15 32.11

[0101] Table 2 Rockwell hardness of the cladding layer on the surface of the straightening roller obtained in the embodiment at different temperatures

[0102] temperature Room temperature 100℃ 200℃ 400℃ 600℃ 700℃ 800℃ Sample 1 47.26 46.41 44.62 42.23 40.21 37.75 32.53 Sample 2 47.81 46.21 44.94 41.92 40.65 37.47 31.61

[0103] Table 3 Rockwell hardness of the cladding layer on the surface of the straightening roller obtained in the embodiment at different temperatures

[0104] temperature Room temperature 100℃ 200℃ 400℃ 600℃ 700℃ 800℃ Sample 1 48.34 47.26 46.41 44.62 42.23 37.75 32.53 Sample 2 49.12 47.81 46.21 44.94 41.92 37.47 31.61

[0105] It can be seen from Tables 1 to 3 that the average hardness of the roller surface cladding layer obtained in Examples to 3 is the highest at room temperature, and the strength of the roller surface cladding layer gradually decreases with increasing temperature. When the temperature exceeds 700°C, the hardness value of the cladding layer decreases significantly.

[0106] The alloy powder in the present invention is used in the repair of the roller surface of the straightening roller, which can significantly improve the high temperature strength and wear resistance of the roller surface. During the cladding, the thickness of one side is 2 to 5 mm and no cracking occurs. According to the feedback from customers, the straightening roller after laser cladding has been used for more than 5 months, and the wear of the roller surface is about 1.5 mm in diameter, and the service life of the roller surface exceeds that of a new straightening roller.

[0107] The composite powder was used to prepare the metallographic specimens for the cladding samples, and the microstructure of the cladding functional layer was observed through metallographic analysis of the specimens. Figure 4 As shown, the cladding layer has a dense structure, uniform grains, no defects such as unfused, pores, and micro cracks, and the cladding layer forms a metallurgical bond with the substrate.

[0108] At this point, those skilled in the art should recognize that, although multiple exemplary embodiments of the present invention have been shown and described in detail herein, many other variations or modifications that conform to the principles of the present invention can still be directly determined or derived based on the content disclosed in the present invention without departing from the spirit and scope of the present invention. Therefore, the scope of the present invention should be understood and recognized as covering all these other variations or modifications.

Claims

1. A method for repairing the roller surface of a straightening roller, characterized in that: The repair method comprises the following steps: Pre-treating the surface of the straightening roller; The surface of the straightening roller is laser clad using alloy powder.

2. The method for repairing the surface of a straightening roller according to claim 1, characterized in that: The laser cladding of the roller surface of the straightening roller comprises: Preheating treatment: preheating the roller surface for cladding, the preheating time is 20 to 35 minutes, and the preheating temperature is 120 to 150 ° C; Formulate a cladding plan, plan the cladding method and cladding path, the cladding method is to use iron-based powder with a hardness of HRC36-40 to lay the base layer, and then use alloy powder for cladding; the cladding path is to use iron-based powder with a hardness of HRC36-40 to rotate and clad along the radial direction of the roller surface, and then use a spiral circle method, along the axial direction of the straightening roller, and unidirectional cladding; Prepare a cladding program, and prepare the cladding program according to the cladding plan; Laser cladding, cladding a bottom layer and a functional layer on the surface of the straightening roller in sequence according to the cladding procedure, wherein the material of the bottom layer is iron with a HRC of 36 to 40, and the material of the functional layer is alloy powder; After cladding, the cladding surface is treated to remove powder residue, and then the surface forming quality and size of the cladding layer are inspected, and then the cladding layer is wrapped with insulation materials and unloaded and placed on a bracket for slow cooling.

3. The method for repairing the surface of a straightening roller according to claim 2, characterized in that: The laser source of the laser cladding is a fiber laser, the powder feeding method is gas-borne coaxial powder feeding, and the gas source is argon.

4. The method for repairing the roller surface of a straightening roller according to claim 1, characterized in that: The pretreatment of the surface of the straightening roller comprises: Removing cracks and fatigue layers from the surface of the straightening roller; Grinding and flaw detection of the cracks and fatigue layers; After confirming that the straightening roller is not damaged, the roller surface and the surface of the straightening roller are cleaned with acetone and dried.

5. The method for repairing the surface of a straightening roller according to claim 3, characterized in that: The parameters of the laser cladding include: The cladding power is 4500-5200W, the cladding spot diameter is 3.8-4.2mm, the cladding line speed is 30-50mm / s, the powder feeding amount is 45-60g / min, the powder feeding gas flow rate is 5-7NL / min, the shielding gas flow rate is 15-20NL / min, the overlap rate is 35%-50%, and the single layer thickness is 2-3.5mm.

6. An alloy powder for repairing the roller surface of a straightening roller, characterized in that: The alloy powder is a high-carbon iron-based alloy, and the high-carbon iron-based alloy contains tungsten, titanium, molybdenum, niobium, silicon, boron, and rare earth elements.

7. The alloy powder according to claim 6, characterized in that The alloy powder has the following components: C: 3.6-6.5%, Cr: 11.5-13.7%, W: 13.2-16.7%, Mo: 8.6-11.5%, Mn: 2.2-5%, Ti: 34.6-41.2%, Si: 0.3-0.7%, Ni: 4.5-7.3%, Nb: 2-4.5%, V: 0.8-1.2%, B: 0.5-2%, rare earth elements (Sc, Hf, Ce) 0.8-2.5%, and the balance is iron Fe.

8. The alloy powder according to claim 6, characterized in that The particle size of the alloy powder is 50-250 meshes.

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